1. Field
Aspects of the present invention relate to an image forming apparatus such as a laser printer and to a processing unit and a toner box which can be mounted to and removed from the image forming apparatus.
2. Description of the Related Art
In a developing unit in an image forming apparatus, the structure has been proposed to prevent undesired toner leakage, in which a toner box is removably mounted to the case of the developing unit, and the opening and closing operations of a first shutter which blocks a toner ejecting port of the toner box and a second shutter which blocks a toner guiding port of the stirring chamber in the developing apparatus, interlock.
In some developing units, the second shutter is mounted on an arm which is pivotably provided at a boss portion in the outer periphery of a supporting groove of a pair of right and left blankets of the casing of the developing unit, and the first shutter is provided on a lever which pivots about a spindle of the toner box. When the spindle of the toner box is inserted into and fixed to the supporting groove of the developing unit, and in this state, the lever of the toner box is pivoted, an engaging projection provided at the lever of the toner box allows the arm of the developing unit to pivot, and the first shutter and the second shutter to pivotably open and close with the first shutter and the second shutter overlapped with each other.
In such structure where the lever that pivots the first shutter is provided at the toner box, there is generally a fear that the toner inside the toner box may leak when the lever is inadvertently pivoted in the state where the toner box has been removed from the developing unit and the first shutter pivots to open the toner ejecting port. Alternatively, there is also a fear that the toner inside the stirring chamber may leak when the arm is inadvertently pivoted in the state where the toner box has been removed from the developing unit and the second shutter pivots to open the toner guiding port.
Therefore, in known the toner boxes, the first shutter is maintained by a first lock mechanism to block the toner ejecting port after the toner box is removed from the developing unit. At this time, the second shutter is maintained by a second lock mechanism to block the toner guiding port in the developing unit. Consequently, these first and second lock mechanisms prevent inadvertent rotation of the first shutter and the second shutter in the state where the toner box is removed from the developing unit, and thus prevent the leakage of the toner from the inside of the toner box and the inside of the stirring chamber of the developing unit.
However, the first lock mechanism and the second lock mechanism described above are each made of a lock body and a screw and are separate components from the first shutter and the second shutter. When these lock mechanisms are mounted to the first shutter and the second shutter, respectively, the first shutter and the second shutter are required to be formed with a pressing pin and a lock hole, resulting in a complicated structure of the toner box and the developing unit.